Vip3 proteins have been successfully expressed in transgenic plants such as maize and cotton. For example, hybrid transgenic maize plants can express Vip3A proteins at levels which are insecticidal to pest insects and which have no negative impact on the plant phenotype. Thus, the Vip3A trait protects yield and yield potential of hybrid maize plants. However, Vip3 has been observed to cause decreased male fertility in certain inbred maize plants under normal growing conditions. This phenomenon is more prominent in inbred maize plants that are homozygous for a vip3A transgene. The degree to which male fertility is decreased is inbred specific—some inbreds exhibit little or no reduction in male fertility when homozygous for a vip3 gene, other inbreds are somewhat sensitive to Vip3 and exhibit a significant reduction in male fertility when homozygous for a vip3 gene, and other inbreds are highly sensitive to Vip3 and exhibit extremely low or no male fertility when homozygous for a vip3 gene. The degree to which male fertility is decreased is also affected by environmental factors, such as water availability and temperature. In Vip3—induced reductions in male fertility, drought and high temperature conditions exacerbate the reduction in male fertility; however, cooler growth conditions have been shown to mitigate the negative effects of Vip3 expression on male fertility.
Identifying genetic loci that enhance the fertility of maize plants expressing a vip3 transgene could lead to more efficient crop production by allowing for the identification, selection and production of vip3-expressing inbred maize plants with increased male fertility.